Dr G C Khilnani, chairman of pulmonary, critical care, and sleep medicine at Delhi’s PSRI Hospital, says the latest Covid-19 spiral is being caused by more infectious sub-variants. But hybrid immunity and precaution vaccines can neutralise the severity of the disease even as you get repeat infections, he tells Anonna Dutt.
Why Dr G C Khilnani? Dr G C Khilnani is currently the chairman of pulmonary, critical care and sleep medicine at PSRI Hospital in Delhi. He is the former head of the department of pulmonology and sleep medicine at the All India Institute of Medical Sciences (AIIMS) and has been practising for over 40 years. He was part of the expert panel initially constituted by the Delhi government when the pandemic began. He is also a part of several professional bodies and editorial boards of journals.
Incidence of Covid-19 has been spiralling in the country over the last two weeks with the Centre writing to states and urging them not to let their guard down. The states have been asked to increase testing, enhance monitoring of influenza-like illnesses and severe acute respiratory infections, and send samples for genomic sequencing.
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The Union health secretary, in a letter sent to states on Thursday, said 81 per cent of the fresh Covid-19 cases reported in the previous 24 hours were from four states – Maharashtra, Kerala, Delhi and Karnataka.
Why have Covid cases started spiking in several parts of the country, including Delhi?
The current increase in Covid-19 cases, it seems, is due to sub-variants of Omicron itself. Almost all samples being sequenced are that of the BA.2 sub-variant of Omicron (which caused the third wave in the country in January). So, it does not seem like there has been a change in the variant.
However, there has been a general laxity in observing Covid-appropriate behaviour, particularly an increased complacency in not wearing masks, which is one of the reasons behind the increase.
There is another sub-variant of BA.2 Omicron – BA.2.12.1 – that has been first reported in the United States (US) and is known to be around 25 per cent more infectious than the previous Omicron sub-variants. Studies have shown that people who were previously infected with other Omicron sub-variants still remain susceptible to BA2.12.1. Therefore, it is possible for a person to be infected twice by Omicron. In that sense, we might be following the United States, where a lull in cases was followed by an increase caused by various Omicron sub-variants, including BA.2.12.1.
Having said that, immunity from a previous infection – be it caused by any of the variants of Covid-19 – and vaccination provide the best shield. But the protection is against severe disease rather than the infection. Hence, hospitalisations still remain low even in states that are witnessing an increase in cases.
What symptoms are patients manifesting at present?
I can talk about my hospital and the symptom profile remains pretty much the same as what we saw during the January wave or even the slight surge in April. Most people are coming in with sore throat, body ache, high-grade fever, but with more gastrointestinal symptoms such as diarrhoea, fullness of abdomen, nausea and irregularity of bowel movement.
Omicron sub-variants are known to spread faster than the Delta variant that caused the devastating second wave but they are also known to remain in the upper respiratory tract itself. What this means is that Omicron does not usually lead to pneumonia and drop in oxygen saturation as was seen during the second wave. By virtue of that, ICU admissions, oxygen requirements and deaths were much less during the third wave. Most people died with Covid-19 that aggravated their pre-existing conditions and not due to it during the third wave.
Is this the time to ensure masking in public and taking the pending precaution dose?
We are all waiting for the end of the pandemic, but we have to continue wearing masks. Seeing people without masks makes an individual uncomfortable about using the protection themselves. However, even one-way masking – one person wearing the mask and others without it – still gives significant protection. So, you should use it even if no one else is.
And, yes everyone who is eligible for a precaution dose should get it, especially those over the age of 60 and those who have co-morbidities or a compromised immune system. A study from Israel showed that those who took a second booster dose had a lower rate of infection and severity of disease as compared to those who did not, particularly for the elderly and immune-compromised. Also, recent evidence shows that people who are fully vaccinated are likely to develop fewer post-Covid symptoms.
Can we mix vaccines for a precaution dose?
As for mixing of vaccines in India for the precaution dose, there is no robust data. Studies from other countries have shown better immune response with a Pfizer vaccine after the AstraZeneca vaccine (Covishield), but that is not applicable in our country because we do not have the Pfizer vaccine yet.